The present invention relates to a method for the operation of a cover of a tilting sunroof, especially a slide-and-tilt sunroof, for closing the roof opening of a vehicle by means of a cover drive. The cover is arranged in a first relative position in relation to a roof panel surrounding the cover when the vehicle is stationary, and the cover is moved from the first relative position into a second relative position by a vacuum force caused by an air stream when the vehicle is in motion. The invention also relates to a corresponding control device and to a slide-and-tilt sunroof system of a motor vehicle.
German patent publication DE 38 40 724 C2 discloses a slide-and-tilt sunroof of a motor vehicle, in which a cover can be adjusted by means of an electric motor, which is reversible in its direction of rotation, in order to provide an open or closed position of the cover in relation to a roof opening of the motor vehicle.
Mechanical play that is always present and a natural lack of inherent rigidity in the tilt-and-slide sunroof assembly mean that the support forces of the adjusting mechanism are not sufficient to keep the cover in a single resting position both when the vehicle is stationary and when it is moving at high speed. This is due to vacuum forces acting on the cover, which are caused by the air stream flowing past the cover and which give rise to a force component directed towards the outside of the vehicle in the Z-direction of the vehicle and acting on the cover, which displaces the cover outwards from its rest position. As a result, the overlap between the sliding sunroof cover and the roof panel or any seal arranged at the edge of the roof opening is lost, and a gap is created, which leads to pronounced wind and whistling noises. The displacement of the cover, moreover, gives the motor vehicle roof panel a visually unattractive overall appearance.
One known solution is to set the rest position of the cover correspondingly low in the Z-direction of the vehicle. Any vacuum forces occurring due to travel at most displace the cover into a position in which the surface of the cover is essentially flush with the surrounding roof panel. This has the unwelcome disadvantage, however, that water collects on the outside of the cover when the vehicle is stationary.
It should be noted that the mechanical play in the roof guide is necessary for technical reasons, since canting of the cover on the cover support or guide would otherwise frequently occur during the cover operating movement, resulting in operating malfunctions. The inadequate inherent rigidity in the tilt-and-slide sunroof assembly essentially stems from the fact that a compromise always has to be made in the case of vehicle components between mechanical stability and inherent weight, which naturally leads to limitations in terms of stability.
European patent publication EP 0 692 400 B1, moreover, discloses an electrical positioning drive suitable for the operation of such a tilt-and-slide sunroof. The drive has a switch wheel driven by a motor and on which permanent magnetic markings are applied. Hall sensors are also provided, which are arranged in such a way that they generate signals according to the permanent magnetic markings. An electronic unit analyzes these signals together with actuating signals fed in by a user and converts them into corresponding motor signals. The motor then turns the switch wheel on its positioning travel.
One object of the present invention is to specify a method and a control device for the operation of a tilting sunroof as described which avoids the aforementioned disadvantages of the prior art. It is intended, in particular, to create a tilting sunroof system which, even at high vehicle speeds, permits an automatic adjustment of the sliding sunroof cover to the roof panel surrounding the cover.
One characteristic feature of the method proposed according to the invention resides in the registering of a physical variable correlating with the vacuum force and in corresponding adjustment of the position of the cover by means of the cover drive unit counter to the direction of the vacuum force from the second relative position into a third relative position as a function of the variable registered. This enables the cover in its closed position to lie in the same relative position to the roof panel surrounding it at all times, regardless of the driving mode. When correspondingly adjusted, this single zero position gives a visually positive overall impression of the outer surface in the transitional area between cover and adjoining roof panel. Any loss of overlap occurring between the tilting sunroof cover and the surrounding roof panel is compensated for by the fact that the cover is, so to speak, actively returned to the original position, thereby restoring the original overlap. This, consequently, also permits automatic compensation for the mechanical play of the tilting sunroof system and for the lack of inherent rigidity in the tilting sunroof.
In addition, wind and whistling noises often occurring at higher vehicle speeds, together with a separation of the laminar flow, which would lead to an increase in the drag coefficient of the vehicle body, are effectively prevented.
In particular, the method proposed can be easily and cost-effectively applied or implemented without the need for modifications to the tilting sunroof mechanism, the drive mechanism or the control electronics.
The third relative position preferably essentially coincides with the first relative position.
All physical variables having a functional correlation with the vacuum force acting on the tilting sunroof cover may be used as variables correlating with the vacuum force. Thus, for example, the instantaneous speed of the vehicle, the change in the position of the cover occurring in the direction of the vacuum force, or the wind noises occurring on the cover due to the air stream, especially at the transition between the cover and the roof panel surrounding the cover, may be used. These variables may be used both as alternatives and in addition to one another.
In one development of the method according to the invention, provision may be made for adjustment of the position of the cover only once a first threshold value of the variable is exceeded. This facilitates an especially simple and cost-effective implementation of the method, since only one further switch point has to be provided in the tilting sunroof drive. At the same time, the cover drive may also advantageously have an additional shut-off position, which is adopted on exceeding the upper threshold value for the variable and abandoned again when the variable falls below a lower threshold value.
In a further development, provision may be made for continuous registering of the physical variable and continuous, corresponding adjustment of the position of the cover. Although this development calls for greater technical requirements, it is consistent with increased ride comfort and more economical fuel consumption, since the position of the tilting sunroof cover can be (continuously) optimized over the entire speed range.
In a particular development, provision can be made for continuous operation from the first threshold value onwards, it being possible to select the threshold value so that no measurable displacements of the cover occur below the threshold value. The latter assumption is highly realistic inasmuch as the functional correlation between the vehicle speed, for example, and the vacuum force occasioned thereby will generally not be linear, and will certainly for most vehicle bodies follow a higher power correlation, so that an appreciable vacuum is consequently built up only at higher speeds.
The control device likewise proposed according to the invention for the operation of such a tilting sunroof cover provides, in particular, for sensors for registering the physical variable or physical variables, and for control devices generating a cover drive control signal correlating with the particular variable registered. On the basis of the control signal, the cover drive moves the cover from the second relative position into a third relative position, in order as far as possible to restore the overlap of the cover with the roof panel. Depending on the respective physical variable, first sensor devices for registering an instantaneous speed of the vehicle, second sensor devices for registering any variation in the position of the cover occurring in the direction of the vacuum force, and/or third sensor devices for registering wind noises occurring on the cover as a result of the air stream may be provided. The sensor devices may be used as alternatives and in addition to one another.
According to one embodiment, corresponding first, second, and/or third sensor devices may be provided for continuously registering the variable or variables, and control devices may be provided for continuously generating a corresponding control signal for the cover drive.
The tilting sunroof system further proposed according to the invention provides for a cover drive mechanism having an additional mechanical switch or engagement point corresponding to the third relative position of the cover.
In accordance with the aforementioned, the invention may be implemented in widely varying ways, that is by reprogramming of a control program (software) loaded into a control module for operation of the tilting sunroof, or alternatively through minor modifications to the mechanical or electrical part of the tilting sunroof drive.
Furthermore, tilt-and-slide sunroofs operated according to the invention can, with the aforementioned advantages, also be fitted to vehicles, especially motor vehicles, of various types. The advantages are experienced in particular at very high vehicle speeds of 150 km/h and upwards.